Procedures for the use of risk assessment under Part XV.1 of the Environmental Protection Act

2005·0.89 MB·English

October 2005

Procedures for the Use of
Risk Assessment under Part
XV.1 of the Environmental
Protection Act

Ontario Ministry of the Environment

Standards Development Branch

PIBs 5404e
Introduction ...............................................................................................................................1
Section 1. Initiating the Risk Assessment...........................................................................2
1.1. Background to Risk Assessment......................................................................................................2
1.2. When to Consider Risk Assessment................................................................................................2
1.3. Role and Responsibilities of the Risk Assessment Qualified Person.............................................4
1.3.1. Making Certified Statements........................................................................................4
1.3.2. Formation of Risk Assessment Team...........................................................................4
1.4. Preparation for Conducting a Risk Assessment..............................................................................5
1.4.1. Pre-Submission Form...................................................................................................6
1.4.2. Public Communication...............................................................................................10
Section 2. Preparation Of A Risk Assessment Report.....................................................13
2.1. Summary and Recommendations...................................................................................................14
2.2. Conclusions and Recommendations..............................................................................................15
2.2.1. Recommend Property-Specific Soil and/or Ground Water Standards.......................16
2.2.2. Special Considerations for Ground Water Standards.................................................18
2.3. Appendices.......................................................................................................................................19
Section 3. General Guidance for Conducting Risk Assessments to Support Filing a
RSC.....................................................................................................................20
3.1. Principal Elements of Risk Assessment (HHRA and ERA)........................................................20
3.2. Risk Assessment Objectives...........................................................................................................20
3.3. Property Information, Site Plan and Geological Interpretation....................................................21
3.3.1. Property Information..................................................................................................22
3.3.2. Site Plan and Hydrogeological Interpretation of Risk Assessment Property.............22
3.3.3. Subsurface Transport Component of the Conceptual Site Model..............................23
3.3.4. Contaminants of Concern...........................................................................................23
Section 4. Requirements Specific to Human Health Risk Assessment (HHRA)...........30
4.1. Problem Formulation Component of HHRA................................................................................30
4.1.1. Human Health Conceptual Site Model.......................................................................30
4.1.2. Risk Assessment Objectives.......................................................................................31
4.1.3. Discussion of Data Quality.........................................................................................32
4.2. Exposure Assessment......................................................................................................................32
Additional guidance is provided in the following sections of this procedures document.......33
ii
4.2.1. Receptor Characteristics.............................................................................................33
4.2.2. Pathway Analysis.......................................................................................................34
4.2.3. Exposure Estimates....................................................................................................35
4.3. Toxicity Assessment.......................................................................................................................37
Additional guidance is provided in the following sections of this procedures document.......38
4.3.1. Hazard Assessment.....................................................................................................38
4.3.2. Dose Response Assessment........................................................................................38
4.4. Risk Characterization......................................................................................................................40
4.4.1. Quantitative Interpretation of Health Risks................................................................42
4.4.2. Qualitative Interpretation of Health Risk...................................................................46
4.4.3. Special Considerations for Environmentally Sensitive Areas....................................47
4.4.4. Interpretation of Off-Site Impacts to Human Health..................................................47
4.4.5. Discussion of Uncertainty..........................................................................................48
Section 5. Requirements Specific to Ecological Risk Assessment..................................50
5.1. Levels of Assessment for ERA.......................................................................................................50
5.2. Problem Formulation Component of ERA....................................................................................51
5.2.1. Ecological Conceptual Site Model.............................................................................52
5.2.2. Risk Assessment Objectives.......................................................................................53
5.2.3. Discussion of Data Quality.........................................................................................54
5.3. Receptor Characterization...............................................................................................................54
5.4. Exposure Assessment......................................................................................................................57
Further guidance is provided in the following sections of this procedures document.............57
5.4.1. Pathway Analysis.......................................................................................................57
5.4.2. Exposure Estimates....................................................................................................58
5.5. Hazard Assessment Component of ERA.......................................................................................60
5.6. Risk Characterization Component of ERA...................................................................................63
5.6.1. Quantitative Interpretation of Ecological Risk...........................................................63
5.6.2. Qualitative Interpretation of Ecological Risk.............................................................64
5.6.3. Special Considerations for Environmentally Sensitive Areas....................................65
5.6.4. Interpretation of Off-Site Ecological Risks................................................................66
5.6.5. Discussion of Uncertainty..........................................................................................67
Section 6. Risk Management (HHRA and ERA).............................................................69
iii
6.1. Risk Management Performance Objectives..................................................................................71
6.2. Risk Management Measures and Ongoing Monitoring................................................................72
Section 7. Alternative Risk Assessment Procedures........................................................73
7.1. Limited Scope Risk Assessment....................................................................................................73
7.1.1. Source of Exceedance of Groundwater Standard is Located Off Property................75
7.1.2. Use of Full Depth Generic Site Condition Standards When Section 41 of the RSC
Regulation Applies to the Property (Environmentally Sensitive Areas)....................75
7.1.3. Modified Generic Risk Assessment...........................................................................75
7.2. Estimation of Natural Local Background Concentrations............................................................76
7.3. New Science Risk Assessment.......................................................................................................78
7.3.1. No Site Condition Standard in the Soil, Ground Water and Sediment Standards for a
COC............................................................................................................................79
7.3.2. Use of Proprietary Models.........................................................................................80
7.3.3. Probabilistic Models...................................................................................................82
7.4. Wider Area of Abatement Risk Assessment.................................................................................82
Section 8. Risk Assessment Submission and Review Process.........................................85
8.1. Review Process................................................................................................................................85
8.2. Steps in the Risk Assessment Preparation and Review Process..................................................85
8.2.1. Step 1 - Site Assessment............................................................................................85
8.2.2. Step 2 - Preparation of Pre-Submission Form............................................................86
8.2.3. Step 3 - Completion of Risk Assessment...................................................................86
8.2.4. Step 4 - Acceptance / Non-Acceptance of Risk Assessment.....................................87
8.2.5. Step 5 - Site Remediation and filing the RSC............................................................88
Section 9. Publications on Human Health Risk Assessment and Ecological Risk
Assessment.........................................................................................................91
9.1. Useful References for Human Health Risk Assessment...............................................................91
9.2. Useful References for Conducting ERAs......................................................................................93

iv
GLOSSARY
Absorption means the process by which a chemical crosses a biological boundary (for
example, skin, lung, gastrointestinal tract) and enters the circulatory
system following ingestion, inhalation or dermal contact.
Absorbed dose means the amount of a substance that crosses an exposed organism's
biological boundaries (for example, skin, lung, gastrointestinal tract, root
membrane). The term is synonymous with uptake and for human
receptors, is expressed as milligram of chemical per kilogram of body
weight per day (or mg/kg bw-day).
Bioassay means a test (assay) in which one or more characteristics of a substance
(for example potency) is measured by the response of living organisms or
isolated tissues, in the present context is synonymous …..with toxicity
test.
Bioavailability means the fraction of an administered dose, typically oral or inhaled, that
can cross a biological boundary and enter the systemic or circulatory
system (expressed as a unitless value).
Carcinogen means any substance that can cause cancer in living organisms (in the
present context including animals or humans).
CCME means the Canadian Council of Ministers of the Environment.
Chronic Daily Intake means the amount of a chemical (usually expressed as mg/kg bw-day)
to which a person is exposed on a daily basis over an extended period of
time, (for example 70 years f or a carcinogen) (usually expressed as mg/kg
bw-day).
Complete exposure pathway means an exposure pathway that does not have any natural or
man-made barriers that prevents a receptor from being exposed to a
contaminant.
Contaminants of Concern (COC) means contaminants that have been identified in Phase I
and/or detected in Phase II environmental site assessments, including
possible toxic metabolites, at concentrations which exceed relevant site
condition standards, or for which there are no relevant site condition
standards, and including those for which the analytical method used
resulted in detection limits that exceed relevant site condition standards.
CPU means a certificate of property use referred to in Section 168.6 of the EPA.
Delivered target dose means the amount of a substance that crosses the biological boundaries of
an organism (for example skin, gastrointestinal epithelium) and becomes
available for interaction at the target tissue(s) or organ(s).
Dioxin-like means any of three families of polycyclic compounds known chemically
as chlorinated dibenzo-p-dioxins, chlorinated dibenzofurans or co-planar
PCBs with comparable structural and biochemical properties.
v
Detailed Quantitative Ecological Risk Assessment (DQ-ERA) means a detailed risk
assessment as described in 1997 CCME document entitled “A Framework
for Ecological Risk Assessment” and is likely to include toxicity tests
and/or biological field studies.
Dose means the actual quantity of a chemical administered to a receptor or to
which it is exposed (see delivered target dose).
Ecological receptor means a non-human organism identified as potentially experiencing
adverse impacts from exposure to a contaminant, either directly through
contact or indirectly through food chain transfer.
EPA means the Environmental Protection Act, R.S.O. 1990 c. E-19.
Ecological Risk Assessment (ERA) means a component of a risk assessment that evaluates the
likelihood that adverse ecological effects may occur, or are occurring, as a
result of exposure to contaminant(s).
Endpoint means an effect on a human or ecological receptor that can be measured
or modeled and described in some quantitative fashion.
ESA means environmental site assessment.
Exposure assessment means the qualitative or quantitative determination or estimation of the
magnitude, frequency, duration and routes of exposure for the
contaminant, including assessment of the uncertainties associated with the
determination.
Exposure pathway means the physical course/route a contaminant takes from its source o the
receptor of concern.
Exposure point concentration means the concentration in an environmental medium (soil,
water, air, sediment) to which a human or ecological receptor is presumed
to be exposed.
HEAST means Health Effects Assessment Summary Table published by the
United States Environmental Protection Agency.
Human Health Risk Assessment (HHRA) means a component of a risk assessment that
characterizes the nature and magnitude of risks to human health from
exposure to contaminants.
Hazard means the potential of a contaminant to cause harm to an individual,
population or the natural environment. Hazard may refer either to the
contaminant itself or the adverse impact that the contaminant causes.
Hazard quotient means the ratio of a single substance exposure level (for example, dose)
over a specified period of time to a toxicity reference value (TRV) such as
RfD or RfC or RsD or RsC or TDI) for that substance derived from
similar exposure characteristics (for example, duration, frequency, route,
etc.).
vi
Incomplete exposure pathway means an exposure pathway where natural or man-made barriers
effectively prevent a receptor from being exposed to a contaminant.
Intake means the actual quantity of a chemical administered to an organism or to
which it is exposed. Also defined as potential dose, it is expressed as
mg/kg bw- day.
IRIS means the Integrated Risk Information System, a database of human
health effects that may result from exposure to various contaminants found
in the environment, maintained by the United States Environmental
Protection Agency.
Local background means the ambient concentration of a contaminant in the soil, ground
water, air or sediment in the local environment that is representative or
typical of the conditions in an urban or rural setting. Local background
concentrations result from either chemicals that occur naturally in the
environment or chemicals that are emitted by anthropogenic activities
other than from activities being carried out on the property being assessed.
Limited scope risk assessment (LSRA) means a risk assessment completed in accordance with
section 7 of Schedule C in O. Reg. 153/04.
Ministry means the Ontario Ministry of the Environment.
Natural environment means the air, land and water, or any combination or part thereof,
of the Province of Ontario.
Natural local background concentration risk assessment (NLBRA) means a risk assessment
completed in accordance with section 8 of Schedule C in O. Reg 153/04.
New science risk assessment (NSRA) means a risk assessment completed in accordance with
section 9 of Schedule C in O. Reg. 153/04.
Occupational Exposure Limits (OEL) means a general term for limits set for workers
exposure, expressed as a time-weighted average concentration (mg/m3) for
a conventional 8-hr workday and a 40-hr workweek.
On-site means located on the RA property which is owned by the RA property
owner who submitted the risk assessment pre-submission form.
Off-site means located off the RA property, but with implications for the property
under assessment.
PAH means polycyclic aromatic hydrocarbon.
PCB means polychlorinated biphenyls.
Preliminary Quantitative Ecological Risk Assessment (PQ-ERA) means preliminary
quantitative risk assessment as described in 1997 CCME document
entitled “A Framework for Ecological Risk Assessment” is an
intermediate level of quantitative risk estimation for specific VECs
exposed to the contaminants of concern.
vii
Phase one ESA means a phase one environmental site assessment as defined in section
168.1 of the EPA.
Phase two ESA means a phase two environmental site assessment as defined in section
168.1 of the EPA.
Pre-Submission Form (PSF) means a form that includes a description of the RA property and
property ownership, lists the contaminants of concern, potential receptors;
transport and exposure pathways described in the conceptual site model
and provides a proposal for proceeding with the risk assessment.
Property specific standard means a soil, ground water or sediment standard specified in a risk
assessment which has been conducted according to the RSC regulation
and accepted by the Director under section 168.5 of the EPA.
Public communication means the process of communication that promotes discussion between
the RA property owner and the public, and provides the public with the
opportunity to discuss the decisions of the owner.
Public Domain in the context of this document means ‘freeware’ RA models that can be
downloaded from agency sites.
QA/QC means quality assurance/ quality control.
QP means qualified person.
QP means qualified person who is responsible for the supervision of or
ESA
conducting the environmental site assessment for the purposes of section
168.1 of the EPA as set out in subsection 5 of the RSC Regulation.
QP means qualified person who is responsible for conducting or supervising
RA
the risk assessment for the purposes of section 168.1 of the EPA as set out
in subsection 6 of the RSC Regulation.
RA means risk assessment.
Receptor means an organism, person, population or community that is exposed to
contaminant(s).
Record of Site Condition means a document prepared in accordance with Part XV.1 of the EPA
and regulations there under, that includes a summary of the final
environmental condition of a property.
Reference concentration refers to a concentration of a compound in a media to which chronic
(i.e. lifetime) exposure is not expected to cause adverse effects to an
organism.
Reference dose means an estimate of a chronic daily exposure to the general human
population, including sensitive sub-groups, that is likely to be without an
appreciable risk of harmful effects during a lifetime of exposure;
expressed as mg/kg bw- day.
Relative Absorption Factor (also known as relative bioavailability adjustment ) is the
fraction obtained by dividing the absolute bioavailability of a chemical
viii
present in the environmental media by the absolute bioavailability of that
same chemical present in the dosing medium used in the toxicity study
from which the reference dose for human health risk assessment was
determined.
Relative bioavailability is a measure of the difference in extent of absorption among two or
more forms of the same chemical (for example, lead carbonate vs. lead
acetate), different media (for example, food, soil, water), or different
doses. In the context of environmental risk assessment, relative
bioavailability is the ratio of the absorbed fraction from the exposure
medium in the risk assessment (for example, soil) to the absorbed fraction
from the dosing medium used in the critical toxicity study.
Reasonable Maximum Exposure (RME) means the highest exposure that is reasonably
expected to occur on a site. The objective of the RME is to estimate a
conservative exposure scenario (i.e., well above the average scenario,
typically the 95th percentile) that is within the range of likely exposure.
Remediation means the management of contaminants at a property to prevent, minimize
or mitigate damage to human health or the natural environment, so that it
is acceptable for its intended use. In the context of this document,
remediation can include, without limitation, removal, destruction and
containment of toxic substances.
Remedial work plan means a plan to bring about the remediation of the property.
RfC See reference concentration.
RfD See reference dose.
Risk management means the implementation of a strategy or measures to control or reduce
the level of risk estimated by the risk assessment to prevent, eliminate or
ameliorate any adverse effect on the property.
RSC Regulation means Ontario Regulation 153/04, as amended.
RsC means risk specific concentration: the concentration of a contaminant
(expressed in units of μg/m3) corresponding to a specified level of lifetime
risk (for example, 10-6).
RsD means risk specific dose: the dose of a contaminant (, expressed in units of
mg/kg bw-day) corresponding to a specified level of a lifetime risk (for
example, 10-6).
Screening Level Ecological Risk Assessment (SL-ERA) means a primarily qualitative or a
semi-quantitative screening assessment, as described in the 1997 CCME
document entitled “A Framework for Ecological Risk Assessment”, of the
potential environmental risk to specific ecological receptors that have been
determined to be of importance.
Site condition standards means site condition standards as they are defined in the RSC
regulation.
ix
Slope factor means the upper bound estimate of cancer risk per mass of a contaminant
contracted per unit body weight per day, expressed in units of (mg/kg bw-
day)-1.
Site plan when included in a risk assessment report, means a diagram of the RA property
indicating building locations and contaminant or source area distribution.
Threshold means the concentration or dose of a contaminant below which an adverse
impact is not expected to occur.
Tolerable Daily Intake (TDI) means an estimate (with uncertainty spanning about an order of
magnitude) of the amount of a contaminant, generally expressed on a body
weight basis (mg/kg bw-day) that can be ingested daily over a lifetime
without appreciable health effects.
Toxicity test means the determination of the effect of a contaminant on a group of
selected organisms, under defined conditions. An environmental toxicity
test may measure the proportion of organisms affected and/or the degree
of effect shown, after exposure to a whole test soil sample (i.e., undiluted
property soil) or a test soil sediment or water in specific concentrations.
Uptake means in exposure assessment, the amount of a contaminant crossing the
biological boundaries (for example, skin, lung, gastrointestinal tract) of an
organism and reaching the systemic circulation. The term is synonymous
with absorbed dose.
Valued Ecosystem Components (VECs) means specific ecological receptors (species or
habitats) that have been determined to be of ecological importance at the
site in question considering the current and proposed land use.
Wider area of abatement risk assessment (WAARA) means a risk assessment completed in
accordance with section 10 of Schedule C in O. Reg. 153/04.
Percentile (90th, 95th) describes sample data frequency distribution such that 90th or 95th
percent of the data distribution is below that value and 10 or 5 percent of
the data distribution is above that value.
95% UCL for the mean means the 95 percent Upper Confidence Limit (95% UCL) for a mean
and is defined as a value that, when repeatedly calculated for randomly
drawn subsets of size “n”, equals or exceeds the true mean 95% of the
time. The 95% UCL provides a measure of the uncertainty of the mean.
x